RoadBikeReview.com's Forum Archives - General


Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )


Need help with Colngo sizing...can't get it right(12 posts)

Need help with Colngo sizing...can't get it rightsukotto
Aug 7, 2003 9:43 AM
I have been recently riding a 55cm CT1. I wasn't real impressed with the bike at first-it felt solid but sluggish. I didn't understand what everyone was raving about on this bike, until I started thinking that the frame may be too big. The problem is that, on paper, it is a very acceptable fit-5.5cm of standover clearance, 100mm stem with 9cm of drop to the bars-the same dimensions as other 54.5ish top tube bikes I have ridden. I made my purchase based on what other sizes of bike I knew to fit me. Unfortunately, a Colnago doesn't have the same handling characteristics as most bikes-it has a steep seat tube and very slack head tube. With such a slack head tube angle, I probably need more than a 100mm stem to get out over the front wheel for great handling, and the center of gravity feels high as well. I have heard that Colngos fit differently than the standard road bike, which makes sense, due to the geometry (slack head angle, steep seat angle). Reading that Tom Demerly review at trialtir-usa.com, he seems to have had some of the same sizing issues when first purchasing his Colnago-purchasing the bike too big based on what he knew to fit with other brands.

Here is some sizing info on me. I am 5 foot 8, have an 85.5cm floor to pelvic bone, 141cm floor to sternal notch, 56cm arm length (top of shoulder bone to wrist). On my 55cm CT1, I have a 75.2cm distance from BB to top of seat, and 5.5cm of standover clearance. My legs are long, my torso short, so it may be a challenge to get over the front wheel enough to ride the bike as it was designed.

What size would perhaps be an improvement in handling? I was thinking a 54cm or even a 53cm. Sure, I will have more standover, but the bike will be lower and I can run a longer stem. Would this be acceptable on the Colnago? Or am I just stuck with a 55cm (due to my fairly long legs-the 55cm frame "fits" when standover is the primary consideration) and be stuck with mediocre handling (the bike doesn't currently handle any better than the 53cm Lemond Alpe that it replaced). If frame sizing is moving toward fitting the top tube more and the standover less, than can I go down a size or two? Thanks in advance for all of your help.
re: Need help with Colngo sizing...can't get it rightMariowannabe
Aug 7, 2003 10:09 AM
Although you've given plenty of info on your post, I won't pretend to be a fit expert. It does sound as though your stem is too short to get the handling you want out of the Colnago. I ride a 56 C40 and its absolutely the best handling bike I've ridden - I've got a 120 stem.

I suggest you check out this article. It'll give you a lot to go on:
http://www.bikesportmichigan.com/reviews/colnago.shtml
re: Need help with Colngo sizing...can't get it right03Vortex
Aug 7, 2003 10:10 AM
I have same arm length and sternal notch (142 actually) but am 5'9" and ride a Litespeed Vortex 55 with a 110 stem. My cycling inseam is 32in or 81+cm. Your inseam suggests even a 57 vs. the 53 lemond you had or even the 53/54 you are thinking of. The LS and Colnago are measured c-t while the Lemond is measured c-c. Of course a 57 would mean a longer TT but I sense you can handle that with even a longer stem. Is your saddle positioned fore/aft properly or at least the way you want it because that effects reach which in turn also effects stem length.

The CT-1 was the otehr bike I was considering but I opted on the Vortex.
FWIWColnagoFE
Aug 7, 2003 10:30 AM
I use a 110 stem on my MXL. I'm 6'2" with long legs as well and I ride a 62cm frame and it fits great.
It's your imagination...C-40
Aug 7, 2003 11:27 AM
You do have long legs and a short torso, much like mine. I'm 5'-6.5" tall with an 83cm inseam. I've owned both a 55cm and a 54cm Colnago C-40.

Your post does not describe what you consider wrong with the handling. If you were expecting some sort of miracle from the Colnago, I imagine that you're disappointed. Welcome to reality. Most stock bikes handle very much the same because their geometry if very similar. Colnagos are made for long european stage racing, including high speed mountain descents. They don't have the the razor sharp steering of a crit bike, if that's what you're after. For that matter, I can't think of a stock frame on the market that has overly quick steering geometry.

Measure the vertical distance from the top of the top tube to the top of the saddle, near the nose. From the rest of your numbers, I would guess 18-19cm. This tells you immediately that the frame is plenty small. So does the 5.5cm standover clearance, since 3-4cm is enough.

My 54cm C-40 has the saddle only 17cm above the top tube (71cm saddle height). I have about 4cm of standover clearance (83cm inseam - 79cm standover). The bars are about 9cm below the saddle, with NO spacers under the 84 degree stem. I previously rode a 55cm with an 80 degree stem and no spacers. I didn't really notice any significant difference when I changed to a 54cm. Since the TT length was only 3mm shorter, I use the same length stem.

You are mistaken if you think that a smaller frame will lower your center of gravity. You'll be sitting at the same height regardless of the frame size, since bottom bracket heights don't very much, if any. The weight of the frame is a very small part of the total, so a smaller frame will not lower your center of gravity by any significant amount. You are also not looking at the differences in Colnago geometry, which are clearly listed on the Colnago charts.

A 53cm frame, for example, only has an 8mm shorter TT length and a 3mm shorter front-center. If you want to see what a 53cm would handle like, move your saddle forward 1cm and put on a 110mm stem. I will predict that you won't notice any significant difference in handling.

If you buy an overly small frame, the short head tube length can quickly become a problem. I suspect that you use at least 1cm of steering tube spacer now. Buy a frame 2cm smaller and you'll need to increase the stem angle by 20 degrees or add 2cm of spacer to get the bars up to height. The setup will quickly become ugly.

Your concept of "getting over the front wheel" for great handling is a total misconception. I've use 100, 110 and 120 stems on my 54cm C-40 and never noticed any big differences. When I used the 120 stem I had the saddle further forward which would increase the weight on the front wheel, but only by 1% for each 1cm of saddle movement. I currently use a 100mm stem on the 54cm frame, with the saddle set further back for climbing. I haven't noticed any deterioration in handling. Did a winding mountain decent at 40+ just recently and it handled perfectly.
Bianchi handles faster than Colnagokenyee
Aug 7, 2003 12:21 PM
it was a stock one in the $1K range (can't remember the name). I found it a little too twitchy. The Colnago MXL handles faster than a Lemond Nevada.

IMHO, of course :-)

ken
just about anything "steers" faster than colnago...C-40
Aug 7, 2003 1:29 PM
That's no secret. The head tube angles are slack and with a stock 43mm rake, the steering is intentionally a tad slow.
yeah..aint it great?! I love fast downhills on mine (nm)ColnagoFE
Aug 7, 2003 2:01 PM
I liked it...hate twitchy bikes :-)kenyee
Aug 7, 2003 2:27 PM
It's your imagination...dawgcatchr
Aug 7, 2003 2:50 PM
Yes, I have just over 19cm from top of top tube to top of saddle. My drop to the bars is 9cm (I currenly have 2cm of spacers but am planning on reducing that as I get further in to the season and gain flexibility-I am probably the least flexible person alive, as it takes me probably a month of daily streching to be able to finally touch the floor).

When I was running a 110 stem, I had to really get forward in tight descents (much like I sometimes do on my mountain bike when I need the front too hook up) because my center of gravity was pretty far back-I couldn't weight the front wheel (heck, I could barely get to the front of the brake hoods). That has changed with the 100mm stem, so the handling has improved. Mostly though, the 55cm just feels a bit boxy and overly stable, like a pair of race-stock GS skis 5cm too long. Sure, the it is stable, but overall the bike seems slower to react than others I have ridden. I used to own a 54cm Tecnos, but that was a long time ago-it did fit me very well.

I guess what it comes down to is that there is no "perfect" fit for someone of odd proportions. Todd at trialtir suggested that I go down to a 53cm, others such as yourself tell me that 55cm is the correct size. Either bike will be a compromise of some sort.
maybe change the fork rake...C-40
Aug 7, 2003 6:54 PM
A fork with more rake (like 50mm) would speed up the steering response, if that's what you're after. A 45mm wouldn't be enough.

The idea of switching to a 53cm is a very bad idea. Since you're already using 2cm of spacer (about the max for a 1" carbon steerer), you would need a 100 degree (flipped 80) stem on the 53. There would be little improvement from the switch.

If you really want a short top tube frame, there are a number of custom builders who could fix you up. Just be prepared for some toe overlap.
re: Need help with Colngo sizing...can't get it righthppy4u
Aug 7, 2003 1:10 PM
Like you I had purchased a Colnago based on anectodal advice from various riders and admittedly all the hype. In my case I was a long time steel fan so I purchased a Colnago Crystal (54cm) back in 1999ish and rode the bike off and on for the next 4 years. The ride felt very solid but dead. I thought it was the weight of the bike...relative to all the other aluminum/carbon/ti bikes. So I went about trying to lighten what I could. The first change I did was install a Look HSC3 carbon fork (4.5cm rake- this is very important), Cinelli Solido bars, and a Campy Chorus aheadset. I installed everything and retaped the bars and VOILA, the bike was immediately different. The stem length and the overall bar height remained the same. The only change I could attribute the change to was the fork.

The bike went from a long distance hauler that would allow me to eat, drink, remove arm warmers etc. into a fairly twitchy "crit" bike. I know this is only subjective, but the weight of the bike hadn't changed much (about 3/4 of a pound since I had the steel Precisa fork) but the bicycle suddenly became very responsive and extremely maneuverable (sp?). I would strongly encourage you to try it since the cost of the fork from Totalcycling was only $145 + shipping.